| Tank dimensions |
Water |
Oil |
| -Length |
124 |
120 |
| -Width |
298 |
120 |
| -Height |
124 |
90 |
| Volume of tank |
4.582048 |
1.296 |
| Calibration factor |
36.952 |
14.4 |
| |
| Drop in level |
53 |
8.1 |
| Actual consumption during test |
1958.46 |
116.64 |
|
| Evaporation Ratio |
16.79 |
lt. of water / lt. of oil |
| |
18.25 |
kg of water / kg of oil |
| Heat balance across boiler |
| |
| Average feed water temp. |
74.00 |
°C |
| Average Steam Pressure |
10.00 |
kg/cm2 |
| Feed water temperature at
economizer inlet |
40.00 |
°C |
| |
| Enthalpy of saturated steam at above pressure |
664 |
kcal / kg |
| Enthalpy of water at boiling |
185.6 |
kcal / kg |
| |
| Enthalpy of steam at the above evaporation ratio |
409.00 |
|
| |
| Quantity of saturated steam |
62.16 |
% |
| Quantity of water carry over |
37.84 |
% |
| |
| Actual Efficiency of boiler on dry saturated steam |
67.03 |
% |
| Heat loss in hot water |
7.72 |
% |
| |
| Heat gain in economiser |
6.21 |
% |
| Heat loss in feed water tank |
3.45 |
% |
| |
| Useful heat available to process |
72.90 |
% |
|
Comments : Though the boiler efficiency of 84% by indirect method shows
that the performance of boiler is very good. However, due to the design of
non-IBR boilers, there is lot of heat wastage from water carry over and wet
steam. This is normally not accounted in the plant efficiency evaluations.
The
contribution of economiser diminishes as the feed water temperature increases
due to condensate recovery. That is the reason why Useful heat to process is
as low as 72.90% against the Indirect boiler efficiency of 84.40%
Tuning of boiler Boiler efficiency test for both the boilers was
carried out during the Energy Audit study. Major findings of the test before are
as follows: |
| PARTICULAR |
850 kg/hr boiler |
600 kg/hr boiler |
| Average fuel consumption |
40 lt./hr |
31 lt./hr |
| Net Heat available to process |
74.80% |
75.07% |
Efficiency of steam generation
Heat loss in moisture separator
WHR in Economizer
Loss in the FW tank |
67 %
7.72%
8.2%
1.5% |
69.37%
7.44%
6.50%
Nil |
|
| Boiler Tuning: During he Energy Audit study, boiler tuning was done, the tuning of boiler has led to following results: |
| PARTICULARS |
850 kg/hr |
600 kg/hr |
| |
Before Tuning |
After Tuning |
Before Tuning |
After Tuning |
| CO2 % |
13 |
13 |
8 |
11 |
| Temperature at boiler outlet |
450°C |
370°C |
450 °C |
370°C |
| Temperature at Economiser outlet |
210°C |
180°C |
270 °C |
210°C |
| Net useful heat available to process |
74.80 % |
78.97 % |
60.0 % |
75 % |
|
This tuning of boiler is expected to reduce the fuel bill by around
5 to
10% depending upon the operating hours of the boilers. This tuning is done
by reducing the fuel quantity and optimizing the air to fuel ratio. Normally,
the plant operators change the settings arbitrarily. It is, therefore, necessary
to do this exercise periodically.
The minimum monetary saving expected is
Rs. 1.5 Lacs per annum.
WASTE HEAT RECOVERY FROM THERMOPAC
STACK :
The Thermic fluid heater burner has a capacity of 1 Lac
kCal/hr
(corresponding to 10 kg/hr LPG firing.). Flue gas temperature is 300°C &
flow rate is 302 M3/hr.
It is therefore proposed to tap heat content in flue gases by installing
Waste Heat Steam Generator in the stack. |
| WASTE HEAT RECOVERY ECONOMICS: |
| 1. Qty of gases through vent (V2) |
= |
302 M3/hr |
| 2. Temp. of gases through vent (V2) |
= |
300°C |
| 3. Gases can be safely cooled to 150°C |
---------- |
| 4. Waste Heat recovery potential |
= |
302 X 0.25 X (300-150) X 1.2 |
| |
= |
13600 kcal/hr |
|
| Steam qty.(@3 kg/cm2 ) that can be generated
through the available Waste Heat. |
| |
= |
13600/(650-30) |
| |
= |
22 kg/hr |
| Saving on low pressure steam |
= |
22 X 0.60 X 8,000 |
| @ Rs. 0.6/kg steam cost. |
= |
Rs. 1,05,000 per year |
| Total saving out of proposed system |
|
|
| Total |
= |
Rs. 1,05,000/Year |
| Investment Proposed |
= |
Rs. 60,000 |
| Pay Back Period |
= |
7 Months |
|
|
|
